A new theoretical study of Earth-like exoplanets orbiting white dwarf stars, accepted for publication in the Monthly Notices of the Royal Astronomical Society (arXiv.org version), suggests that astronomers could detect oxygen in the atmosphere of one much more easily than for an exoplanet orbiting a Sun-like star. An artist’s impression of a habitable planet orbiting a white dwarf. The ghostly blue ring is a planetary nebula – hydrogen gas...